1. Technical Field
The present invention relates to a board unit, and more particularly, to a board unit which is removably attachable to a board housing frame.
2. Background Art
A technology for detachably attaching a circuit board on which electronic circuit components are mounted such as a print circuit board to a subrack constituting an electronic apparatus unit such as a communication device is known (for example, see “Background Art” in Patent Document 1: International Publication No. W003/086039). In this example, a rectangular parallelepiped subrack 120 has a housing section 121 with an opening 121a on the front side for housing a plurality of circuit boards as shown in FIGS. 12A and 12B. In the housing section 121, guide rails 127, . . . , 127 extend from the opening 121a toward the bottom. Front rails 124 and 124 are provided on the side of the opening 121a in the upper and lower panels of the subrack 120. Each of the front rails 124 has first handle contact parts 125 and second handle contact parts 126.
As shown in FIG. 13, a circuit board 110 has a board connector 115 on its rear end, which is the right end as viewed in the drawing. The circuit board 110 has a front panel 111 on its front end, which is the left end as viewed in the drawing, and a pair of upper and lower insertion-extraction handles 100 and 100 at the upper and lower end of the front panel 111.
As shown in FIG. 14A, each of the insertion-extraction handles 100 has an lockable part 102 on the rear end removably lockable with a handle locking part 112 provided on the circuit board 110, a contactable part 103 having first and second contactable parts 103a and 103b contactable with the first and second handle contact parts 125 and 126, respectively, of the front rail 124 of the subrack 120, and a pivot pin 104, located between the lockable part 102 and the contactable part 103, rotatably attached to a handle attaching member 140 provided on the circuit board 110. Each of the insertion-extraction handles 100 has a pressing operation part 100 with a first pressing operation part 101a and a second pressing operation part 101b at the front end. When the circuit board 110 is inserted into the subrack 120, the lockable parts 102 of the insertion-extraction handles 100 are removed from the handle locking parts 112 as shown in FIG. 14B and the circuit board 110 is inserted into the subrack 120. Then, the first pressing operation parts 101a of the insertion-extraction handles 100 are pressed upward as viewed in FIG. 14B (in the direction indicated by the arrow R1). The insertion-extraction handles 100 are thereby rotated about the pivot pins 104, and the first contactable parts 103a of the insertion-extraction handles 100 are brought into contact with the first handle contact parts 125 of the front rails 124 of the subrack 120. When the insertion-extraction handles 100 are further rotated, the first contactable parts 103a are rotated. Then, the circuit board 110 is moved backward (in the X1 direction in the drawing) with respect to the subrack 120 and the board connector 115 of the circuit board 110 is inserted into a subrack side connector (not shown) in the subrack 120. In this state, the lockable parts 102 of the insertion-extraction handles 100 are engaged with the handle locking parts 112 as shown in FIG. 14A.
When the circuit board 110 having inserted into the subrack 120 is extracted therefrom, the second pressing operation parts 101b of the insertion-extraction handles 100 are pressed downward as viewed in the drawing (the direction indicated by the arrow R2), that is, in the direction opposite the direction in which the first pressing operation parts 101a are pressed. Then, the engagement between the lockable parts 102 and the handle locking parts 112 are released as shown in FIG. 14B, and the second contactable parts 103b of the insertion-extraction handles 100 and the second handle contact parts 126 of the front rails 124 of the subrack 120 are brought into contact with each other. When the insertion-extraction handles 100 are further rotated, the second contactable parts 103b are rotated. Then, the circuit board 110 is moved forward, that is, leftward as viewed in the drawing (in the X2 direction in the drawing), with respect to the subrack 120 and the board connector 115 of the circuit board 110 can be extracted from the subrack side connector 123 in the subrack 120.
The insertion-extraction handles 100 of the circuit board 110 are made of a synthetic resin and so shaped that they can have resiliency as shown in FIG. 14A. As a result, the lockable parts 102 of the insertion-extraction handles 100 are urged toward the handle locking parts 112 so that the insertion-extraction handles 100 can be locked to the circuit board 110 with a prescribed locking force. This configuration prevents the circuit board 110 inserted into the subrack 120 from being easily extracted from the subrack 120.
It is, however, difficult to obtain a desired locking force only by changing the shape of the insertion-extraction handles 100. Also, the insertion-extraction handles 100 have a problem in durability. When the insertion and extraction of the circuit board 110 are repeated or the circuit board 110 is left for a long period of time, the locking force may be lowered because of wear or creep of the lockable parts 102 and/or the handle locking parts 112. Further, since the handle locking parts 112 have to be fixedly provided on the circuit board 110, the production process is complicated and the production cost is high.